Magnet head



Sept. 16, 1958 H. THIELE MAGNET HEAD Filed Jan. 14, 1955 United StatesPatent 0 MAGNET HEAD Heinz Thiele, Kiel-Wik, Germany, assignor to Zeisslkon A. G., Stuttgart, Germany Application January 14, 1955, Serial No.481,940

1 Claim. (Cl. 179-1002) The invention relates to improvements inmagnetheads which consist of at least two ferro-magnetic platespositioned side by side and in which the pole shoe ends are spaced fromeach other apart by a non-magnetic foil having the thickness of thedesired gap, whereby the pole shoes are facing each other with theirlargest surface area. These magnet heads, among others, have theadvantage that the wear caused on the pole shoes by the magnetic tapetraveling transversely over the same does not cause any change in thewidth of the gap. Unfortunately, the magnetic efficiency of such headconstruction leaves much to be desired. The pole shoes form namely amagnetic shunt which is of more or less influence, depending upon thesize of the surface areas of the pole shoes which are spaced from eachother by the intermediate layer of the non-magnetic foil.

It is an object of the invention to reduce harmful shunt elfects and soimprove the magnetic efficiency of magnet heads by recessing the poleshoe ends, with the exception of those end portions of the pole shoelocated in direct proximity to the efiective gap-such that the producedgreater space between the two pole shoe plates Will reduce the magneticshunt to an extent which is no longer disturbing.

Other objects and advantages of the invention will become apparent fromthe following description taken together with the accompanying drawings,in which:

Fig. 1 represents a pair of pole shoes of conventional constructionwhich is embedded in a block of synthetic material as diagrammaticallyindicated, and

Fig. 2 shows a pair of pole shoes according to the invention.

Referring to Fig. l which illustrates a magnet head of conventionalconstruction, a pair of pole shoe plates 1 2,852,617. Patented Sept. 16,1958 and 2, made of a pair of ferro-magnetic material, is embedded in ablock 3 made of a plastic material. The magnet head is excited by a coil4 placed around the overlapping leg portions 8 and 9 of the plates 1 and2. The ferro-magnetic plates 1 and 2 face each other with their largestsurface area and the non-magnetic gap is formed by thickness of anon-magnetic foil 5 which is placed between the pole shoe ends 6 and 7.

The magnetic head according to the present invention is shown in Fig. 2.Pole shoe plates 1a and 2a consisting of ferro-magnetic material againconfront each other with their largest surface area and the pole shoeends 61: and 7a are spaced apart from each other by a nonmagnetic foil5a having the thickness of the desired gap 10.

In order to reduce or to eliminate any magnetic shunt action between theconfronting faces of the pole shoe ends 6a and 7a, each of said shoeends in the zone of the gap is provided with a recess 10 and 11,respectively, which preferably extends at opposite sides of pole shoeends and across the entire Width of the pole shoe ends and in closeproximity of the face portions engaging the foil 5a and forming the gap.

What I claim is:

In a magnetic head, a pair of ferro-magnetic core plates having legportions provided with laterally extending foot and head portions, saidcore members being oppositely arranged with their foot and head portionsin overlapping relation, the laterally extending head portions beingspaced from each other to form a gap 'therebetween and the overlappingfoot portions being arranged to form the core for a conductor winding, anon-magnetic foil of a thickness equal to the space of said gap mountedin said gap between said overlapping head portions, and the innersurfaces of said head portions being provided with V oppositely disposedgrooves arranged adjacent said gap to extend parallel to the lengththereof and across the entire Width of the head portions such as todecrease the surface areas of the head portions of the core membersforming said gap.

References Cited in the file of this patent UNITED STATES PATENTS2,711,945 Kornei .Iune 28, 1955

